Contact block assembly with interlock secured by means of a single screw



March 17, 1970 D. F. wu cox 3,501,603 CONTACT BLOCK ASSEMBLY WITH INTERLOCK SECURED BY MEANS OF A SINGLE SCREW Filed July 5, 1968 2 Sheets-Sheet 1 fiz/azzjor .DQ/c? fflzzfcox 0 0 w 2 J 6 1w- M w J r llllllll 1 z 8 i .125: 4 w 5 2 J m M O d w i Em flfi flilm n 7 MH r. HQ l1 h m \\M M W w I us" D. F. WILLCOX March 17, 1970 CONTACT BLOCK ASSEMBLY WITH INTERLOCK SECURED BY MEANS OF A SINGLE SCREW 2 Sheets-Sheet 2 Filed July 5, 1968 flQ/e lax/002 (one M 9' Za- United States Patent 3,501,603 CONTACT BLOCK ASSEMBLY WITH INTERLOCK SECURED BY MEANS OF A SINGLE SCREW Dale F. Willcox, Aurora, 111., assignor to Furnas Electric Company Batavia, 111., a corporation of Delaware Filed July 5, 1968, Ser. No. 742,797 Int. Cl. H0111 9/26 U.S. Cl. 20050 3 Claims ABSTRACT OF THE DISCLOSURE The push button station assembly of this invention employs a pair of push buttons which actuate the respective plungers of the duplex switch device operatively associated'with the push buttons. A pivotally mounted interlocking member is provided for preventing simultaneous actuation of the push buttons so that the operator cannot activate bothelectric circuits at the same time. A single securing screw secures the duplex switch to a supporting frame and assists in mounting the interlocking member.

The invention relates to electric switches of the type adapted to be actuated by push buttons and has reference in particular to interlocking means for a switch assembly having a pair of push buttons.

Push buttons for actuating switch structure may be carried by a cover plate which may be either a face plate or a general purpose enclosure plate. When a pair of such push buttons are employed for actuating a pair of electric switches to start or stop an electric motor or the like it is desirable to prevent operation of one electric circuit while the other one is activated.

Accordingly an object of the invention is to provide an interlocking member which will prevent the simultaneous operation of both push buttons in a dual push button assembly whereby to prevent the simultaneous operation of both circuits of a duplex switch device associated therewith.

Another object of the invention resides in the provision of an interlocking member for the purposes described, which will be relatively simple in design and which will have convenient means for mounting the same in place on the contact block of the duplex switch device so that oscillating movement can take place.

With these and other objects in view, the invention may consist of certain novel features of construction and operation as will be more fully described and particularly pointed out in the specification, drawings and claims appended hereto.

In the drawings which illustrated an embodiment of the device and wherein like reference characters are used to designate like parts.

, FIGURE 1 is a front elevational View of a cover plate which mounts a pair of push buttons;

FIGURE 2 is a rear elevational view of the cover plate structure of FIGURE 1;

FIGURE 3 is a plan elevational view showing a general purpose enclosure box with a duplex switch device and theinterlocking member of the invention in mounted relation on the base thereof;

FIGURE 4 is a transverse sectional view taken substantially along line 4-4 of FIGURE 1, and showing the cover plate and enclosure box with push button and switch device;

FIGURE 5 is a longitudinal sectional view taken substantially along line 5-5 of FIGURE 1;

FIGURE 6 is a side elevational view of the present switch assembly and which shows the interlocking memher in one oscillated position;

FIGURE 7 is a side elevational view similar to FIGURE 3,501,603 Patented Mar. 17, 1970 6 but which shows the interlocking member in its second oscillated position;

FIGURE 8 is a detail sectional view taken substantially along line 88 of FIGURE 3 and showing the pivoting arrangement for the interlocking member; and

FIGURE 9 is an exploded view showing the two parts of the present interlocking device.

Inv FIGURE 1 a metal cover or metal face plate 10 is shown and which mounts a pair of push buttons 11 and 12 by means of which an electric switch device can be actuated. The push buttons are similar in design and in operation to those disclosed and claimed in the co-pending application of Willcox Ser. No. 728,297 filed May 10, 1968 and entitled Push Button Station Assembly. The cover plate may have bevelled edges and two spaced openings 13 and 14 are forced in the same with each opening having an inwardly directed annular flange 15. A metal bracket 16 of generally rectangular shape FIGURE 2, is fixed to the underside of the face plate 10 by means of the flanged supporting legs 17 and the rivets which receive the screws 18.

A pair of openings 20 are formed in the wall of the bracket 16 and each opening is provided with the diametrically extending lugs 21. The openings 20 are approximately the same in diameter as the openings 13 and 14 and the said pairs of openings are in alignment so that each may receive and mount a push button such as 11 and 12. The said push buttons are tubular in formation and the sameare molded of any suitable plastic of the desired color. The maximum diameter of the push button is slightly less than the diameter of the aligned openings which are to receive the same, FIGURE 5, since the push button must have a free, loose fit to permit actuation thereof against a backing coil spring. Each button has a front wall 22 which is integral with a cylindrical skirt 23, with the front wall being apertured for receiving the legs of an insert 24 and the said wall being integral with a diametrical rib 25. The skirt is slotted to receive the lugs 21 and it will be observed that a coil spring 26 is confinedwithin the skirt 23 between the front wall 22 and the lugs 21. The force exerted by the coil spring maintains the push button in extended position with the flange 27 in contact 'with the inwardly directed flange 15 provided by the face plate.

It is necessary to assemble the push buttons with the face plate 10 before the bracket 16 is riveted or secured to the underside of the said plate. Also, in order to accommodate the coil spring 26, the rib 25 is not integral with the skirt 23. In fact a slot is provided on each side of the rib for receiving the convolutions of the coil spring. The push buttons 11 and 12 are adapted to be actuated by being depressed to in turn actuate electric switch structure which is supported on the base wall of an enclosure box such as 30 as shown in FIGURES 4, 5 and 6. The box is open since the lid is formed by the cover plate 10. Thus the base or bottom wall 31 is integral with the two end walls 32, the side walls having been eliminated for more convenient access to the base which supports the duplex type switch contact block 33. A similar type of duplex switch device is shown in the co-pending application of Willcox filed May 10, 1968 Ser. No. 728,288 and entitled Supporting Frame Structure for Push Button Station Assemblies.

The contact block or housing 33 which is formed by molding from any suitable insulating material is provided with four terminals such as indicated by numeral 34. A screw 35 is associated with each terminal for securing the electrical conductor to the terminal and a bridging member 36 may be employed for connecting the two inside terminals. The contact block houses a pair of normally open contacts and a pair of normally closed contacts. The movable bridging contact for each said pair is actuated by a spring backed plunger 37 and by a plunger 38. The contact block 33 is mounted on the inside surface of the base wall 31 by a securing screw 38, FIGURE 8. The contact block is accurately positioned on the base wall by lugs 40 on the bottom of the contact block which enter the slots 41 in the base wall. When the contact block is properly positioned the screw 38 will have threaded relation 'with an opening in the base wall for mounting the switch device within the enclosure box. Also with the switch device in mounted position it will be understood that the plungers 37 and 38 are in direct alignment with the rib 25 of the push buttons 11 and 12 respectively. Accordingly when the push buttons are depressed the plungers are operated to in turn actuate the contacts of the switch.

To prevent simultaneous operation of both circuits of a duplex contact block such as 33, the invention provides an interlocking member designated in its entirety by the numeral 42 FIGURE 9 and which includes a pair of laterally spaced cam portions 43 and 44 on the top edge of the member. An opening '45 is formed in the member about centrally thereof and this opening receives the tongue 46 of the auxiliary support 47.

The mounting of the interlocking member 42 is effected by the screw 38 which thus has a dual function Since the screw also fastens the contact block 33 in place. The head of the screw 38 has location in a groove 48 in the contact block and a shoulder 50 is formed so that the tongue 46 has contact therewith. This firmly secures the auxiliary support in place since it will be observed that the screw passes through an opening in the tongue. The tongue thus has contact against the shoulder whereas the base of the support 47 has contact with the bottom wall of te ennlosure box. Since the tongue passes through the opening 45 in the interlocking member the said member is supported for osillating movement and the same is positioned so that the rib 25 of the push buttons will engage the cam portions '43 and 44 respectively.

It is believed that the operation of the device will be fairly understood from what has been described. When the push button 14 is depressed for starting an electric motor or for other similar purposes the interlocking member '42 is oscillated and the member takes a position as shown in FIGURE 6 which prevents the simultaneous actuation of the stop button 13. The operator having started the motor by'depressing the button 14, he now releases the button which returns to its extended position. For stopping the motor the push button 13 is depressed as shown in FIGURE 7 and here again the interlocking member is oscillated so as to prevent the simultaneous actuation of the start button 14.

The invention is not to be limited to or by details of construction of the particular embodiment thereof illustrated by the drawings, as various other forms of the device will be apparent to those skilled in the art without departing from the spirit of the invention or the scope of the claims.

What is claimed is:

1. In a push button station assembly, a cover plate having a pair of openings therein, a bracket in fixed relation on the rear side of the cover plate, said bracket having a pair of openings therein of approximately the same diameter and in alignment with the openings in the cover plate, a push button located in each of said aligned openings and supported for movement to and from an extended and depressed position, a supporting frame secured to the cover plate and bracket combination, a contact block in supported relation on the base member of respectively with the plungers, whereby when a push button is depressed its plunger is actuated to in turn actuate its switch, an interlocking member supported on the base of the supporting frame for oscillating movement, said interlocking member being oscillated by actuation of the push buttons in a manner to prevent the operator from actuating both electric circuits of the duplex switch means at the same time, and a single securing screw securing the contact block and thus the electric switch means to the base member of the supporting frame, said securing screw having the additional function of assisting in the mounting of the interlocking member on the base member of the supporting frame for oscillating movement.

2. In a push button station assembly as defined by claim 1, additionally including an auxiliary support having a projecting tongue, said interlocking member having an opening for receiving the tongue and wherein said single securing screw secures the tongue to said contact block in addition to securing the contact block to the base member of the supporting frame, whereby the interlocking member is mounted for said oscillating movement with the tongue forming the pivot axis of the same.

3. In a cover plate and bracket combination, a cover plate having a pair of spaced openings, a bracket in fixed relation on the rear side of the cover plate, said bracket including a base portion in spaced relation to the cover plate and having a pair of spaced openings in alignment with those in the cover plate, a push button located in each of said pairs of aligned openings and being mounted for movement to and from an extended and depressed position, a supporting frame providing a base member, said frame being releasably secured to the cover plate and bracket combination, a contact block fixed to the base member and providing duplex switch means having a pair of switch actuating plungers, a diametrically disposed rib comprising part of each push button and which is aligned with one of said plungers, whereby when a push button is depressed its plunger is actuated to in turn actuate its switch, an interlocking member in pivotal associated relation with the contact block and adapted to have operative relation with the said push buttons, said interlocking member having oscillating movement in a manner to prevent simultaneous actuation of both push buttons so that the operator cannot activate both electric circuits a the same time, an auxiliary support having a projecting tongue, said interlocking member having an opening for receiving the tongue, and a single securing screw for securing the tongue to the contact block and for additionally securing the contact block to the base member of the supporting frame, whereby the interlocking member is mounted for said oscillating movement with the tongue of the auxiliary support forming the pivot axis for the interlocking member.

References Cited UNITED STATES PATENTS 2,713,092 7/1955 Rucks et al 20050.3 X 3,086,090 4/1963 Carroll 200-159 X 3,182,160 5/1965 Zavertnik et al. 2,836,666 5/1958 Nolden et al. 2005 3,322,927 5/1967 Waldorf et al.

FOREIGN PATENTS 1,348,334 11/1963 France.

952,725 10/ 1956 Germany. 1,037,556 8/ 1958 Germany.

ROBERT K. SCHAEFER, Primary Examiner ROBERT A. VANDERHYE, Assistant Examiner US. Cl. X.R. 

